If we HAD to mess with the current selection process, maybe one good idea would be to have an Olympic Trials 18-24 months before the Olympics and choose a group of guys (5?, 10?) who would be eligible for the Olympics.
Then you could do a number of different things from this pool of people. First, you could have them run off against each other in various distances (they wouldn't all have to be marathons). There would be at least one marathon somewhere in there to determine how everyone is developing. Perhaps they would all train together for a year (not necessarily easy to coordinate).
This method would have these benefits:
1. Still have an Olympic Trials with all the benefits previously mentioned (except for having your team set in stone).
2. Great team building amongst 5-10 potential Olympians (which also adds a new "stepping stone" for guys who can make the trials but not necessarily the team).
3. Consistency of performance would be a part of the selection process.
4. A good guy having a bad day isn't eliminated.
5. If the team trained together (at least a good part of the time) we might learn as a nation how to run team tactics for things like World XC (see Athens Olympic 10k for a primer on how 3 guys (Ethiopia) working together can pull each other to higher levels)...note that the USATF 5k (Hall and Dobson) show that this is already happening in some places.
6. If one of the real Olympians gets a serious injury, you have more than one ready replacement who is actually still training for the Olympics rather than digging up the 4th place guy who probably stopped planning to be at the Olympics and may be working out with another goal in mind (10k trials, later marathon, etc).
The downfall of changing to this format is that it is logistically difficult (how do you get 10 guys to train in the same place using the same program?). This would be less of an issue if there were large sponsorship dollars behind the effort (i.e. they all got a fat salary to work together for a year or two).
I still like the Trials format as it is...